Metal salt extractant, composition, method for recovering metal salts, and method for producing metal salts

Abstract

To provide an extractant for selectively extracting at least one of divalent cobalt salt and divalent nickel salt.SOLUTION: The present invention provides a metal salt extractant for extracting at least one of divalent cobalt salt and divalent nickel salt. The extractant is represented by general formula (1). In the formula (1), R1 and R2 each independently represent a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxy group, or a group represented by -NHR', R' represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxy group, and X1 and X2 each independently represent an oxygen atom or a sulfur atom.SELECTED DRAWING: None

Description

Technical Field

[0001] One embodiment of the present invention relates to a metal salt extractant, a composition, a method for recovering a metal salt, and a method for producing a metal salt.

Background Art

[0002] In the automotive industry, information and communication technology industry, etc., many metal resources are used. On the other hand, due to the increasing global demand for metal resources, the uneven distribution of metal resource reserves, etc., there is concern that the reduction of the circulation volume of metal resources, price hikes, etc. may be caused. Therefore, attempts have been made to extract and recycle metal resources from industrial waste. In recycling, it is possible to provide products that meet the requirements of various industrial fields by extracting a single metal resource with high purity.

[0003] Among metal resources, transition metals have similar properties because they have the same electron configuration in the outermost shell, and the technology for extracting a single transition metal from multiple types of transition metals is complex. When the transition metal forms a metal salt rather than a simple metal substance, by recovering the transition metal in the state of the metal salt, the recovered transition metal salt can be recycled as it is. However, in the recycling of metal salts, the technology for separating and recovering transition metal salts according to the difference in metal species is even more complex.

[0004] Cobalt and nickel are widely used as the positive electrode materials of lithium-ion batteries. Due to the rapid capacity expansion of lithium-ion batteries in recent years, such as in electric vehicles, it is desired to establish a method for selectively and efficiently recovering these metal salts in the future.

[0005] Among the technologies for extracting metal resources from materials, there is chemical separation, and metal resources can be extracted with high purity using chemical reactions, electrolysis reactions, etc. Among them, the method of separating metals using an extractant in a solvent can perform precise separation of a specific metal.

[0006] On the other hand, one technique for recovering ions from a solvent is to capture anions in the solvent using anion receptors. Depending on the molecular structure of the anion receptor, it is possible to selectively capture the target ion species. Non-patent documents 1 and 2 disclose anion receptors having a urea group at the 8,8'-position of a 2,2'-binaphthyl group. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] S. Kondo, H. Sonoda, T. Katsu, and M. Unno, Sens. Actuators B, 160, 684-690 (2011). [Non-Patent Document 2] S. Kondo, M. Nagamine, S. Karasawa, M. Ishihara, M. Unno, and Y. Yano, Tetrahedron, 67, 943-950 (2011). [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] As mentioned above, cobalt II and nickel II are metal resources that play an important role in industry, and recovery from industrial waste and efficient extraction from ores are expected to increase the supply of these resources. For example, a method of selectively extracting and separating divalent cobalt salts and divalent nickel salts from materials using extractants is useful.

[0009] On the other hand, the anion receptors disclosed in Non-Patent Documents 1 and 2 have a relatively rigid skeleton because their basic structure consists of a 2,2'-binaphthyl group linked to rigid naphthyl groups by single bonds, and furthermore, the urea group introduced at the 8,8'-position is positioned appropriately, allowing them to capture anions. However, the anion receptors disclosed in Non-Patent Documents 1 and 2 tend to have low solubility in non-aqueous solvents due to their rigid structure resulting from the 2,2'-binaphthyl group, which limits their applications.

[0010] One object of the present invention is to provide an extractant that selectively extracts at least one of a divalent cobalt salt and a divalent nickel salt. Another object of the present invention is to provide a simple method for extracting, recovering, or producing at least one of a divalent cobalt salt and a divalent nickel salt. [Means for solving the problem]

[0011] The gist of this invention is as follows: [1] A metal salt extractant that extracts at least one of a divalent cobalt salt and a divalent nickel salt, and is a compound represented by the following general formula (1). [ka] (In general formula (1), R 1 and R 2 Each is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group, and X 1 and X 2 These are, independently, either an oxygen atom or a sulfur atom.

[0012] [2] The metal salt extractant described in [1], which is a compound represented by the following general formula (2). [ka] (In general formula (2), R 3 and R 4 are each independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxy group, and X 1 and X 2 are each independently an oxygen atom or a sulfur atom.)

[0013] [3] In the general formula (2), R 3 and R 4 are each independently an n-butyl group, a tert-butyl group, or a phenyl group, the metal salt extractant according to [2]. [4] In the general formula (2), X 1 and X 2 are sulfur atoms, the metal salt extractant according to [2]. [5] A composition comprising the metal salt extractant according to any one of [1] to [4] above and a non-aqueous solvent. [6] A method for recovering a metal salt using the metal salt extractant according to any one of [1] to [4] above.

[0014] [7] A method for separating at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material and producing at least one of a divalent cobalt salt and a divalent nickel salt, the method comprising: preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of [1] to [4], and a non-aqueous solvent; and subjecting the mixture to solid-liquid separation to obtain a metal salt-containing liquid, a method for producing a metal salt.

[0015] [8] A method for separating at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material and producing at least one of a divalent cobalt salt and a divalent nickel salt, the method comprising: preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of [1] to [4], and a non-aqueous solvent; subjecting the mixture to solid-liquid separation to obtain a metal salt-containing liquid; and recovering the metal salt extractant from the metal salt-containing liquid, a method for producing a metal salt. [Effect of the Invention]

[0016] According to one embodiment of the present invention, an extractant can be provided for selectively extracting at least one of a divalent cobalt salt and a divalent nickel salt. According to another embodiment of the present invention, a simple method can be provided for extracting, recovering, or producing at least one of a divalent cobalt salt and a divalent nickel salt. [Modes for carrying out the invention]

[0017] One embodiment of the present invention will be described below, but the present invention is not limited by the following examples.

[0018] "Metal salt extractants" One embodiment of the metal salt extractant is a metal salt extractant that extracts at least one of a divalent cobalt salt and a divalent nickel salt, and is a compound represented by the following general formula (1).

[0019] [ka]

[0020] (In general formula (1), R 1 and R 2 Each is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group, and X 1 and X 2 These are, independently, either an oxygen atom or a sulfur atom.

[0021] Hereinafter, compounds represented by general formula (1) will also be collectively referred to as metal salt extractants.

[0022] This metal salt extractant is capable of capturing at least one of divalent cobalt salts and divalent nickel salts in a non-aqueous solvent and can be used to extract at least one of divalent cobalt salts and divalent nickel salts from a non-aqueous solvent. In particular, this metal salt extractant is excellent at selectively capturing chloride ions released into a non-aqueous solvent, and by capturing them together with at least one of their counterions, divalent cobalt ions and divalent nickel ions, it becomes possible to extract them in the form of at least one of nickel II chloride (CoCl2) and nickel II chloride (NiCl2).

[0023] An anion receptor having a urea group at the 8,8'-position of the 2,2'-binaphthyl group has a rigid structure due to the 2,2'-binaphthyl group and excellent anion-capturing association ability due to having urea groups at both ends. This compound is shown by the following general formula (10).

[0024] [ka]

[0025] (In general formula (10), R is an n-butyl group, a tert-butyl group, or a phenyl group.)

[0026] Compared to the compound represented by general formula (10), the compound represented by general formula (1) has a structure in which the binaphthalene skeleton is replaced with a skeleton having an aliphatic chain and an oxygen atom (O) or a sulfur atom (S). Due to its flexible structure, it is thought to exhibit high solubility in non-aqueous solvents. In the compound represented by general formula (1), the amide bonds at both ends are expected to associate with anions, particularly halide ions such as chloride ions. Furthermore, in general formula (1), R 1 and R 2The imino group is present, and it is predicted that the association ability with anions will be further enhanced by the introduction of urea groups at both ends. On the other hand, due to its flexible structure, the association ability with anions tends to decrease. Considering its high solubility in organic solvents, it is possible to efficiently capture anions from organic solvents by adding these compounds to organic solvents at high concentrations. Furthermore, since they can be added to non-aqueous solvents at high concentrations, it is possible to reduce the amount of non-aqueous solvent used in extraction processes.

[0027] The compound represented by general formula (1) is thought to have stronger interactions with the cation when an oxygen atom (O) or sulfur atom (S) is introduced. Furthermore, the introduction of an aliphatic chain of an appropriate length relative to the ionic radius of the cobalt II ion or nickel II ion between the two oxygen atoms (O) or sulfur atoms (S) allows for selective capture of the cobalt II ion or nickel II ion. In this way, the cobalt II ion or nickel II ion and its counter anion are captured within a single molecule, allowing it to function as an extractant for at least one of the divalent cobalt salt and the divalent nickel salt. Compared to other transition metal ions such as manganese II ions, cobalt II ions and nickel II ions are softer, and the soft ligand sulfur atom coordinates strongly, enabling selective capture.

[0028] In general formula (1), R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', and R' may be a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group. In general formula (1), R 1 and R 2 They may be the same or different from each other.

[0029] R 1 and R 2The alkyl group introduced may be a linear alkyl group or a branched alkyl group, and may be linear or alicyclic. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. Examples of this alkyl group include linear alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, decyl, and dodecyl groups; and alicyclic alkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, or groups in which at least one hydrogen atom of these is substituted with an alkyl group. Among these, linear alkyl groups are preferred, alkyl groups with 1 to 4 carbon atoms are more preferred, and even more preferably n-butyl or tert-butyl groups.

[0030] R 1 and R 2 The aryl group introduced as such preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms. This aryl group may be monocyclic, polycyclic, or fused, and may have 1 to 4 aromatic rings, or a fused ring of 2 to 4 aromatic rings, and preferably has one benzene ring. Examples of this aryl group include phenyl, naphthyl, anthracenyl, phenantrenyl, tetracerenyl, biphenyl, terphenyl, and fluorenyl groups. Among these, the phenyl group is preferred. These aryl groups may have at least one hydrogen atom substituted with an alkyl group, for example, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms, specifically, p-tolyl, m-tolyl, and o-tolyl groups.

[0031] R 1 and R 2The heteroaryl group introduced is a group having a carbon atom and a heteroatom on a ring, and examples of heteroatoms include nitrogen, oxygen, sulfur, silicon, boron, and phosphorus atoms. The total number of atoms of carbon and heteroatoms in this heteroaryl group is preferably 5 to 24, more preferably 6 to 12, and even more preferably 6 to 8. Examples of this heteroaryl group include groups having a 6-membered heteroaromatic ring such as pyridine and pyrazine, groups having a condensed heteroaromatic ring such as quinoline, isoquinoline, acridine, and phenanthroline, and groups having a 5-membered heteroaromatic ring such as furan, pyrrole, and thiophene.

[0032] R 1 and R 2 The alkoxy group introduced may have a linear or branched alkyl group as the alkyl group portion, and may be linear or alicyclic. The alkoxy group preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. The alkoxy group is represented, for example, as -O-R', where R' represents an alkyl group, specifically as described above for alkyl groups. More preferably, alkoxy groups having 1 to 4 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy, sec-butoxy, and isobutoxy groups.

[0033] R 1 and R 2 In the group represented by -NHR' which is introduced as, R' is the R described above. 1 and R 2 The functional groups described above are examples.

[0034] Preferably, R 1 and R 2Each of these is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 24 carbon atoms, a heteroaryl group having 5 to 24 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, or a group represented by -NHR'. Here, R' is preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 24 carbon atoms, a heteroaryl group having 5 to 24 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group. More preferably R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -NHR', and among these, an alkyl group having 1 to 8 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, or a group represented by -NHR' is preferred. Here, R' is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or a hydroxyl group, and more preferably an alkyl group having 1 to 8 carbon atoms or a heteroaryl group having 6 to 12 carbon atoms. In a preferred example, R 1 and R 2 Each of these is independently an alkyl group having 1 to 4 carbon atoms, an aryl group having 6 to 8 carbon atoms, or a group represented by -NHR' (where R' is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 8 carbon atoms), and more preferably an n-butyl group, a tert-butyl group, a phenyl group, or a group represented by -NHR (where R' is an n-butyl group, a tert-butyl group, or a phenyl group). In a more preferred example, R 1 and R 2 At least one of them is a tert-butyl group or -NHR' (where R' is a tert-butyl group), and more preferably R 1 and R 2 Both are tert-butyl groups or -NHR' (where R' is a tert-butyl group).

[0035] In general formula (1), X1 and X 2 Each of these may independently be an oxygen atom (O) or a sulfur atom (S). 1 and X 2 They may be the same or different from each other. Preferably, X 1 and X 2 They are identical to each other, and more preferably X 1 and X 2 Both are sulfur atoms (S).

[0036] An example of a compound represented by general formula (1) is R 1 and R 2 Examples include compounds in which the group is represented by -NHR'. Specifically, these are compounds represented by the following general formula (2).

[0037] In general formula (2), R 3 and R 4 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group, and X 1 and X 2 These are, independently, an oxygen atom (O) or a sulfur atom (S). For details on each functional group, see R 1 and R 2 The things explained above can be listed.

[0038] [ka]

[0039] In general formula (2), R 3 and R 4 Each of these is preferably an alkyl group, and the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 8, and even more preferably 1 to 4. 3 and R 4 Each of these groups, independently, preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms, if it is an aryl group. Specifically, R 3 and R 4Each of these groups is independently preferably an n-butyl group, a tert-butyl group, or a phenyl group, with the tert-butyl group being preferred.

[0040] Specific compounds are listed below. In the structural formulas below, n-Bu represents an n-butyl group, t-Bu represents a tert-butyl group, and Ph represents a phenyl group.

[0041] [ka]

[0042] Among the compounds described above, compounds 2a, 2b, and 2c are preferred, with compound 2b being more preferred, from the viewpoint of the solubility of the compound and the solubility of the complex with the metal salt. The compounds described above may be provided as individual compounds or as mixtures.

[0043] "Methods for synthesizing compounds" The following describes a method for synthesizing the compound represented by general formula (1). Note that the compound in one embodiment is not limited to the compound synthesized by the following synthesis method. Because the compound represented by general formula (1) has a relatively simple molecular structure, the synthesis procedure is also simple, and it can be synthesized in a single reaction from commonly used starting compounds.

[0044] One example of a method for synthesizing a compound represented by general formula (1) may involve introducing an isocyanate derivative, a carboxylic acid halide, etc., into the compound represented by general formula (3) below. In general formula (3), X 1 and X 2 Each of these is independently either an oxygen atom or a sulfur atom.

[0045] [ka]

[0046] More specifically, one example of a method for synthesizing the compound represented by general formula (2) may include introducing an isocyanic acid derivative to the amino groups at both ends of 1,2-bis(2-aminoethoxy)ethane or 1,2-bis(2-aminoethylthio)ethane.

[0047] The isocyanate derivative is a compound represented by R''NCO. R'' is R in general formula (2). 3 and R 4 These are groups introduced as such, and the details are as described above. Specifically, examples of isocyanate derivatives include alkyl isocyanates and aryl isocyanates. Examples of alkyl isocyanates include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, n-butyl isocyanate, sec-butyl isocyanate, tert-butyl isocyanate, isobutyl isocyanate, pentyl isocyanate, hexyl isocyanate, and cyclohexyl isocyanate. Examples of aryl isocyanates include phenyl isocyanate.

[0048] This reaction can be carried out in various solvents. Suitable solvents include, for example, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, and diethylene glycol; ether solvents such as diethyl ether, diethylene glycol dimethyl ether, and tetrahydrofuran; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; ester solvents such as ethyl acetate and γ-butyrolactone; and water. Non-aqueous solvents used in the compositions described later may also be used as solvents. After the reaction, the solvent and other components may be removed from the reaction mixture as needed, and the product can be obtained by filtration and drying. Alternatively, the product may be isolated using chromatography for further purification.

[0049] 1,2-bis(2-aminoethoxy)ethane and 1,2-bis(2-aminoethylthio)ethane can be synthesized according to conventional methods, and commercially available products may also be used, for example.

[0050] "composition" According to one embodiment, a composition comprising a metal salt extractant and a non-aqueous solvent can be provided. As the metal salt extractant, the metal salt extractant according to the above embodiment can be used. This composition can be used to extract at least one of a divalent cobalt salt and a divalent nickel salt. For example, by mixing this composition with a metal salt-containing material containing at least one of a divalent cobalt salt and a divalent nickel salt, the metal salt extractant can selectively capture at least one of the divalent cobalt salt and the divalent nickel salt from the metal salt-containing material, and dissolve at least one of the divalent cobalt salt and the divalent nickel salt in a non-aqueous solvent.

[0051] At least one of the divalent cobalt salt and the divalent nickel salt to be extracted can be any type of salt, regardless of its solubility in non-aqueous solvents. Examples of divalent cobalt salts include cobalt-II chloride (CoCl2), coBr2, CoI2, and other cobalt-II halides. Examples of divalent nickel salts include nickel-II chloride (NiCl2), NiBr2, NiI2, and other nickel-II halides. The divalent cobalt salt and the divalent nickel salt may be used individually or in combination of two or more types.

[0052] Various non-aqueous solvents can be used without particular limitations. Examples of non-aqueous solvents include: cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; linear carbonates such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, and dipropyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone; compounds having a nitrile group such as acetonitrile; linear ethers such as 1,2-dimethoxyethane and dimethoxymethane; tetrahydrofuran, 1,3 -Ether compounds such as cyclic ethers like dioxolane, 1,4-dioxane, 1,3-dioxane, and 2-methyltetrahydrofuran; chain carboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate; compounds having a sulfonyl group such as sulfolane, propanesultone, 3-methylsulfolane, and 2,4-dimethylsulfolane; phosphate esters such as trimethyl phosphate and triethyl phosphate; and may include methylene chloride, cyclopentanone, cyclohexylbenzene, 3-methyl-1,3-oxazolidine-2-one, and dimethyl sulfoxide.

[0053] The non-aqueous solvent may be a compound having substituents such as fluorine atoms or chlorine atoms, or the non-aqueous solvent may be a compound in which fluorine atoms or chlorine atoms have been substituted. For example, it may be a compound having one or more fluorine atoms or chlorine atoms in a cyclic carbonate, linear carbonate, ether compound, or linear carboxylic acid ester. Specifically, examples include fluoroethylene carbonate and chloroethylene carbonate. Chloroform is another example.

[0054] The non-aqueous solvents described above may be used individually or in combination of two or more. When using two or more non-aqueous solvents in combination, it is preferable to use a combination that forms a single phase in the composition.

[0055] The composition may be a non-aqueous composition, for example, one in which the water content is limited to 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less relative to the total amount of the composition, and may be substantially water-free. A lower water content allows for more stable maintenance of the metal salt extractant in the composition.

[0056] In the composition of one embodiment, the metal salt extractant is preferably present in a molar ratio of 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, per 1 unit of non-aqueous solvent. In the composition of one embodiment, the metal salt extractant is preferably present in a molar ratio of 1 or more, more preferably 5 or more, and even more preferably 10 or more, per 1 unit of salt.

[0057] Compounds represented by general formula (1) have a structure capable of capturing one cobalt II ion or nickel II ion and a counterion per molecule. Therefore, metal salts can be recovered within the range of one cobalt II ion or nickel II ion per molecule of the compound represented by general formula (1), and the amount of metal salt extractant to be used should be determined according to the predicted amount of metal salt recovered.

[0058] Furthermore, the composition according to one embodiment may be a composition that is liquid at 30°C, and more preferably a composition that is liquid at 25°C. The composition according to one embodiment may also have reduced fluidity at lower temperatures, becoming gel-like or solid.

[0059] The composition of one embodiment can be used, for example, in a method to recover at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material and to produce at least one of a divalent cobalt salt and a divalent nickel salt. In another example, the composition of one embodiment can be used in a method to recover at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method to adsorb at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method to adsorb and remove at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method to purify at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method to purify at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material and to produce a high-concentration metal salt composition.

[0060] "Method for producing metal salts" According to one embodiment, a method for producing at least one of a divalent cobalt salt and a divalent nickel salt by separating them from a metal salt-containing material is provided, comprising the steps of: preparing a mixture containing a metal salt-containing material, a metal salt extractant, and a non-aqueous solvent; and separating the mixture into solid and liquid phases to obtain a metal salt-containing liquid. The metal salt extractant can be the metal salt extractant according to the above embodiment.

[0061] The metal salt-containing material is not particularly limited as long as it may contain at least one of a divalent cobalt salt and a divalent nickel salt. If the metal salt-containing material is solid, it is preferable that it be in powder, crushed, or granular form from the viewpoint of efficiency of dissolution or dispersion. The metal salt-containing material may be minerals or industrial waste. In this case, the minerals or industrial waste may be decomposed, dismantled, crushed, etc., and then physically separated according to shape, magnetic force, electrical properties, specific gravity, etc., to prepare the metal salt-containing material. The metal salt-containing material may also be waste liquid after a chemical reaction such as a catalytic reaction, industrial waste liquid, etc.

[0062] The metal salt-containing material is preferably water-free. For example, the water content may be limited to 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less relative to the total amount of the metal salt-containing material, and may be substantially water-free. If the metal salt-containing material contains water, the stability of the metal salt extractant may be impaired during the extraction process. The metal salt-containing material may be prepared in a dissolved or dispersed state in a non-aqueous solvent and mixed with the metal salt extractant and the non-aqueous solvent in this state. The non-aqueous solvent used here may be one of those described in the section on non-aqueous solvents included in the above composition.

[0063] The divalent cobalt salts and divalent nickel salts that may be included in the metal salt-containing material may be one or more of those described above, or two or more may be included in combination. The metal salt-containing material may contain only one or both of the divalent cobalt salt and the divalent nickel salt as metal salts, or it may contain impurities in addition to one or both of the divalent cobalt salt and the divalent nickel salt, or it may contain other metal salts in addition to one or both of the divalent cobalt salt and the divalent nickel salt. Other metal salts are not particularly limited, but examples include salts of monovalent transition metals, salts of divalent transition metals, salts of trivalent transition metals, salts of tetravalent or higher polyvalent transition metals, salts of alkali metals, salts of alkaline earth metals, etc. Specifically, examples include manganese-II chloride (MnCl2), iron-II chloride (FeCl2), copper-II chloride (CuCl2), zinc chloride (ZnCl2), sodium chloride, potassium chloride, magnesium chloride, calcium chloride, etc. These may be included individually or in combination of two or more types.

[0064] For example, a metal salt extractant according to one embodiment can selectively capture and extract divalent transition metals, such as at least one of divalent cobalt salts and divalent nickel salts, and is therefore useful for selectively recovering at least one of divalent cobalt salts and divalent nickel salts from various transition metal salts.

[0065] The content of divalent cobalt salt and divalent nickel salt in the metal salt-containing material is not particularly limited, and the divalent cobalt salt and divalent nickel salt can be recovered whether in trace or large amounts. For example, the total amount of divalent cobalt salt and divalent nickel salt is preferably 0.1 to 100% by mass, and more preferably 40 to 80% by mass, relative to the total amount of the metal salt-containing material.

[0066] Next, the process of preparing a mixture containing a metal salt-containing material, a metal salt extractant, and a non-aqueous solvent will be described. The method of mixing these components is not particularly limited; they can be added to a container all at once or in portions and mixed using a stirrer or the like. Alternatively, a composition containing a metal salt extractant and a non-aqueous solvent may be prepared in advance, and the metal salt-containing material may be added to this composition all at once or in portions and mixed. The reactivity of the mixture can be increased by heating it. The heating temperature is preferably 30 to 100°C, more preferably 50 to 100°C, and even more preferably 80 to 100°C. The heating time can be set appropriately depending on the scale of the reaction system, the heating temperature, the type and shape of the materials, etc., and may be, for example, 10 minutes to 5 hours, or 1 to 2 hours. Heating may be carried out continuously or intermittently from the preparation of the mixture to the solid-liquid separation of the mixture.

[0067] In the mixture, the metal salt extractant is preferably at a molar concentration of 0.01 to 1 M, and more preferably at 0.05 to 1.0 M. In the mixture, the amount of metal salt-containing material varies depending on the assumed amounts of divalent cobalt salt and divalent nickel salt contained therein, but for example, it is preferably at 0.1 to 100% by mass, and more preferably at 40 to 100% by mass, relative to the total amount of the mixture.

[0068] Next, the process of obtaining a metal salt-containing liquid by solid-liquid separation of the mixture will be described. Solid-liquid separation can be carried out by methods such as filtration, centrifugation, and sedimentation. In the filtration method, filter paper, filter cloth, membrane filters, etc., can be used. The resulting metal salt-containing liquid may contain a non-aqueous solvent, a metal salt extractant, and divalent cobalt salt and divalent nickel salt. If the metal salt-containing material contains other components besides divalent cobalt salt and divalent nickel salt, and these other components do not dissolve in the non-aqueous solvent, these other components can be removed as solids by solid-liquid separation.

[0069] A step of recovering the metal salt extractant from the metal salt-containing solution may be included after the step of obtaining the metal salt-containing solution. For example, solvent extraction is a method for recovering the metal salt extractant from the metal salt-containing solution. In the solvent extraction method, at least one of the divalent cobalt salt and the divalent nickel salt can be separated into the extraction solvent by mixing the metal salt-containing solution with an extraction solvent that is immiscible with the non-aqueous solvent contained in the metal salt-containing solution and capable of dissolving at least one of the divalent cobalt salt and the divalent nickel salt. Water is suitable as the extraction solvent in this case. Since the metal salt-containing solution after separating at least one of the divalent cobalt salt and the divalent nickel salt contains the metal salt extractant and the non-aqueous solvent, the metal salt extractant can be reused.

[0070] The following describes a specific procedure for extracting metal salts. (Step 1) Sample: Sample 1 is crushed powder from a used lithium-ion secondary battery. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0071] Sample 1, a metal salt extractant, and a non-aqueous solvent are mixed to obtain a mixture. The mixture is stirred and / or heated to partially dissolve the solids in the mixture. The mixture is separated into solid and liquid components to remove the solids and obtain a metal salt-containing solution. At this time, if the sample contains the target metal salt, at least one of the divalent cobalt salt and the divalent nickel salt is selectively captured by the compound represented by general formula (1), dissolved in the non-aqueous solvent, and recovered as a metal salt-containing solution.

[0072] (Step 2) Sample 2: This sample is waste liquid from the semiconductor material manufacturing process. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0073] Step 2 is the same as Step 1 except that the sample is changed. In this case, if the sample contains the target metal salt, at least one of the divalent cobalt salt and the divalent nickel salt is selectively captured by the compound represented by general formula (1), dissolved in a non-aqueous solvent, and recovered as a metal salt-containing solution. [Examples]

[0074] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, t-Bu represents a tert-butyl group and Ph represents a phenyl group.

[0075] "Examples of metal salt extraction tests" (Synthesis method for compound 4b) The following compound 4b was synthesized. [ka]

[0076] (Synthesis method) A solution of 500 mg of 1,2-bis(2-aminoethoxy)ethane (obtained from Tokyo Chemical Industry Co., Ltd.) and tert-butyl isocyanate (735 mg) in tetrahydrofuran (6 mL) was refluxed under an argon atmosphere for 18 hours. The solution was cooled, and the resulting colorless solid was filtered by suction to obtain compound 4b (804 mg, 69%) represented by (4b) above. Mp 151~156°C.

[0077] 1 H NMR (500 MHz, CDCl3) δ 5.46 (s, 2H), 5.15 (s, 2H), 3.75 (s, 4H), 3.56 (t,4H, J = 4.6 Hz), 3.31 (q, 4H, J = 4.6 Hz), 1.33 (s, 18H). 13 C NMR (126 MHz, CDCl3) δ158.2, 70.8, 70.2, 50.1, 40.0, 29.5.

[0078] (Synthesis method for compound 2b) The following compound 2b was synthesized. [ka]

[0079] (Synthesis method) Under an argon atmosphere, tert-butyl isocyanate (0.65 mL, 5.51 mmol, 2.0 eq) was added in small amounts by syringe to a 10 mL solution of 1,2-bis(2-aminoethylthio)ethane (499 mg, 2.77 mmol) in THF (10 mL) at room temperature. The reaction mixture was stirred at room temperature for 3 hours, cooled, and then evaporated under reduced pressure. The residue was recrystallized from THF to obtain the product as a colorless solid. Yield: 470 mg, 45%. Mp: 161.0~162.1°C.

[0080] 1 H NMR (500 MHz, CDCl3) δ 5.13 (t, 2H, J = 5.5 Hz), 4.73 (s, 2H), 3.35 (dt, 2H, J1= 6.6, J2= 5.5 Hz), 3.78 (s, 4H), 2.69 (t, 4H, J = 6.6 Hz), 1.33 (s, 18). 13 C NMR (126 MHz, CDCl3) δ 157.6, 50.3, 40.0, 32.6, 32.1, 29.6.

[0081] (Evaluation of the solubility of metal salts 1) Table 1 shows the evaluation results for combinations of solvent, host, and guest, and the solubility of the guest metal salt. According to the combinations shown in Table 1, a composition of CHCl3 (chloroform), a solvent containing 0.05 M of host compound 4b or 2b, was prepared by adding an equimolar amount of the guest to the host. The mixture was then heated and stirred at 70°C for 0.5 hours. After cooling to room temperature (25°C), the solubility of the mixture was visually observed within 30 minutes. "None" in Table 1 represents the case where no host was added; the mixture was prepared using the same procedure except for the absence of a host, and the solubility was observed. Solubility was evaluated based on the following criteria. The results are shown in the table. +++: Dissolves to about 0.05M ++: Dissolves to about 0.01M +: Indicates coloration derived from salt. -: Does not dissolve and does not show coloration.

[0082] [Table 1]

[0083] The results shown in the table indicate that CoCl2 can be extracted in CHCl2 in the presence of compound 4b or compound 2b. NiCl2 can be extracted in CHCl2 in the presence of compound 2b. Since MnCl2 and ZnCl2 do not dissolve in CHCl2 in the presence of compound 4b or compound 2b, respectively, it can be concluded that at least one of CoCl2 and NiCl2 can be selectively separated in the presence of at least one of MnCl2 and ZnCl2. Considering the solubility of FeCl2 itself in CHCl2, it can be inferred that FeCl2 is not captured by compound 4b or compound 2b in CHCl3.

[0084] (Evaluation of the solubility of metal salts, part 2) Table 2 shows the evaluation results for combinations of solvent, host, and guest, and the solubility of the guest metal salt. According to the combinations shown in Table 2, a composition of MeCN (acetonitrile), a solvent containing 0.05 M of host compound 4b or 2b, was prepared by adding an equimolar amount of guest to the host. This mixture was then heated and stirred at 50°C for 1 hour. After cooling to room temperature (25°C), the solubility of the mixture was visually observed within 10 minutes. In Table 1, "none" indicates the case where no host was added; the mixture was prepared using the same procedure except for the absence of a host, and the solubility was observed. Solubility was evaluated based on the following criteria. The results are shown in the table. +++: Dissolves to about 0.05M ++: Dissolves to about 0.01M +: Indicates coloration derived from salt. -: Does not dissolve and does not show coloration.

[0085] [Table 2]

[0086] The results shown in the table indicate that NiCl2 can be extracted in MeCN in the presence of compound 2b. Since MnCl2 and ZnCl2 do not dissolve in MeCN in the presence of compound 4b or compound 2b, respectively, it can be concluded that NiCl2 can be selectively separated in the presence of at least one of MnCl2 or ZnCl2. FeCl2 can be separated due to its low solubility. CoCl2 was not tested because it is soluble in MeCN.

[0087] "Evaluation of meeting size" Compounds 4b and 2b were synthesized and prepared as described above.

[0088] (Method of synthesizing compound 4c) The following compound 4c was synthesized. [ka]

[0089] (Synthesis method) A solution of 1,2-bis(2-aminoethoxy)ethane (obtained from Tokyo Chemical Industry Co., Ltd.) and phenyl isocyanate (1.77 g) in tetrahydrofuran (10 mL) was refluxed under an argon atmosphere for 1 hour. The solution was cooled, evaporated under reduced pressure, and the residue was recrystallized from ethyl acetate to obtain compound 4c (2.51 g, 95%) as a colorless solid. Mp 130.0~130.5°C.

[0090] 1H NMR (500 MHz, CDCl3) δ 7.62 (s, 2H), 7.34 (dd, 4H, J1 = 8.6, J2 = 1.2 Hz), 7.24 (dd, 4H, J1 = 8.6, J2 = 7.2 Hz), 7.00 (t, 2H, J = 7.2 Hz), 5.53 (t, 2H, J = 5.2 Hz), 3.65 (s, 4H), 3.60 (t, 4H, J = 5.2 Hz), 3.40 (q, 4H, J = 5.2 Hz).

[0091] (Synthesis method for compound 2c) The following compound 2c was synthesized. [ka]

[0092] (Synthesis method) Under an argon atmosphere, phenyl isocyanate (0.60 mL, 5.55 mmol, 2.0 eq) was added in small amounts by syringe to a solution of 1,2-bis(2-aminoethylthio)ethane (503 mg, 2.79 mmol) in THF (10 mL) at room temperature. The reaction mixture was stirred under reflux for 3 hours, cooled, and then evaporated under reduced pressure. The residue was recrystallized from THF to obtain the product as a colorless solid. Yield: 397 mg, 35%. Mp: 181.1~194.9°C.

[0093] 1 H NMR (500 MHz, DMSO-d6): d 2.64 (t, 4H, J = 6.86 Hz), 2.75 (s, 4H), 3.26 (dt, 4H, J1= 6.86, J2= 5.82 Hz), 6.28 (t, 2H, J = 5.82 Hz),6.88 (tt, 2H, J1=7.50, J2=1.00 Hz), 7.20 (dt, 4H, J1= 6.88, J2= 1.83 Hz), 7.37 (dd, 4H, J1= 8.52, J2= 1.22 Hz), 8.58 (s, 2H).

[0094] (Evaluation of meeting volume) Table 3 shows the results of evaluating the association constants for various anion and extractant combinations. (5.0 × 10⁶ in a 5 mL volumetric flask) -3 Prepare a CD3CN solution containing M 2b or 4b, and use this solution to measure 5.0 × 10 in a 2 mL volumetric flask. -2 A solution containing M TBAAcO (tetrabutylammonium acetate) or TBACl (tetrabutylammonium chloride) was prepared. 500 μL of the 2b or 4b solution was added to the NMR tube using a microsyringe, and the solution was analyzed in the absence of anions. 1 The 1H NMR spectrum was measured. Then, the guest solution, prepared using a microsyringe, was added in an equivalent volume. 1 The procedure for measuring 1H NMR was repeated several times. Based on the measured data, the association constant was determined by performing curve fitting using the nonlinear least squares method. The reproducibility of the results was confirmed by repeating the measurement three times, and the average value was calculated. The results are shown in Table 3.

[0095] [Table 3]

[0096] As shown in the table, compounds 4b and 4c and compounds 2b and 2c all contain chloride ions (Cl - ) and acetate ions (AcO - It can be seen that they associate with ). From this, it can be inferred that compounds 4b, 4c and compounds 2b, 2c are capable of capturing divalent cobalt salts and divalent nickel salts of various anions.

[0097] "Evaluation of solubility in solvents" Compounds 4b and 2b were synthesized and prepared as described above.

[0098] (Evaluation of solubility) Table 4 shows the combinations of solvents and extractants, and the results of solubility evaluation. Each receptor was added to the measurement solvent while heating, allowed to cool, and saturated solutions were obtained by centrifugation and filtration. 500 μL of the saturated solution was added to an NMR tube using a microsyringe and evaporated. After drying under reduced pressure, 100 μL of a 2 mM naphthalene-containing CDCl3 solution and 400 μL of CDCl3 were added. 1 1H NMR was measured. In 2a and 2c, 100 μL of a DMSO-d6 solution containing 4 mM naphthalene, prepared in a 5 mL round-bottom flask, was added to 400 μL of DMSO-d6. 1 1H NMR was measured. Based on the measurement results, solubility was calculated from the ratio of the integral values. The results are shown in Table 4.

[0099] [Table 4]

[0100] As shown in the table, compounds 4b and 2b are soluble in various solvents. From the results of the "Evaluation of Metal Salt Extraction" above, it can be seen that compound 4b or compound 2b captures at least one of CoCl2 and NiCl2 in CHCl3 or MeCN. Considering this, it is thought that any solvent that dissolves compound 4b or compound 2b to the same extent as CHCl3 or MeCN can be used as a solvent when extracting at least one of CoCl2 and NiCl2 using compound 4b or compound 2b. [Industrial applicability]

[0101] Metal salt extractants according to several embodiments of the present invention can be used to extract at least one of divalent cobalt salts and divalent nickel salts from various materials. For example, it is possible to extract at least one of divalent cobalt salts and divalent nickel salts from industrial waste, industrial wastewater, wastewater after chemical reactions, etc. In particular, it is possible to selectively extract at least one of divalent cobalt salts and divalent nickel salts from various transition metal salts. Specifically, it can be used to extract at least one of divalent cobalt salts and divalent nickel salts from waste or wastewater during the manufacturing process of battery materials, semiconductor materials, substrate materials, etc., used waste or wastewater therefrom, wastewater from catalytic reactions, etc. By extracting at least one of divalent cobalt salts and divalent nickel salts using this metal salt extractant or a composition containing the same, it is possible to recover, produce, adsorb, remove, or purify at least one of divalent cobalt salts and divalent nickel salts.

Claims

1. A metal salt extractant that extracts at least one of a divalent cobalt salt and a divalent nickel salt, and is a compound represented by the following general formula (1). 【Chemistry 1】 (In general formula (1), R １ and R ２ Each is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group, and X １ and X ２ These are, independently, either an oxygen atom or a sulfur atom.

2. The metal salt extractant according to claim 1, wherein the compound is represented by the following general formula (2). 【Chemistry 2】 (In general formula (2), R ３ and R ４ Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group, and X １ and X ２ These are, independently, either an oxygen atom or a sulfur atom.

3. In the general formula (2), R ３ and R ４ are each independently an n-butyl group, a tert-butyl group, or a phenyl group, and the metal salt extractant according to claim 2.

4. In the above general formula (2), X １ and X ２ The metal salt extractant according to claim 2, wherein is a sulfur atom.

5. A composition comprising a metal salt extractant and a non-aqueous solvent according to any one of claims 1 to 4.

6. A method for recovering a metal salt using a metal salt extractant according to any one of claims 1 to 4.

7. A method for separating at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material to produce at least one of a divalent cobalt salt and a divalent nickel salt, A step of preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of claims 1 to 4, and a non-aqueous solvent, A method for producing a metal salt, comprising the step of separating the mixture into solid and liquid phases to obtain a metal salt-containing liquid.

8. A method for separating at least one of a divalent cobalt salt and a divalent nickel salt from a metal salt-containing material to produce at least one of a divalent cobalt salt and a divalent nickel salt, A step of preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of claims 1 to 4, and a non-aqueous solvent. The process involves separating the mixture into solid and liquid components to obtain a metal salt-containing liquid, and A method for producing a metal salt, comprising the step of recovering the metal salt extractant from the metal salt-containing liquid.

Images